Motion picture film-advancing mechanism

ABSTRACT

A motion picture film-advancing mechanism for advancing film having sprocket holes therein in stop-and-go fashion through a film gate for exposure or projection comprising a film-advancing finger means carried on spaced cranks for movement in a circular path for engaging the film and advancing it intermittently in a cyclic action, and a register pin carried for axial movement in a mounting block and having an eccentric drive for moving the register pin intermittently into engagement with the film sprocket holes for holding the film when the finger is retracted, said register pin drive and finger drive mechanism being synchronized through a common gear train and forming for a highspeed operation; the improvements including pivotally carrying the register pin mounting block and providing an eccentric adjustment screw for adjusting the pivot of the block and providing fine adjustment of the register pin to obtain accurate adjustment of the spacing between the register pin and finger, providing a lost motion drive for the register pin whereby the register pin may be retracted while the finger is in a retracted position, and providing means for eliminating play and backlash including a pressure bearing member on a ball bearing mounting for the retractable fingers.

United States atent [72] inventor Ernest M. Whitley Palo Alto, Calif.[21] Appl. No. 782,132 [22] Filed Dec. 9, 11968 [45] Patented Aug. 17,1971 [73] Assignee Red Lake Laboratories Santa Clara, Calif.

{54] MU'iliON PICTURE FiLM-ADVANCHNG MlEiCiiiiAMSM 12 Claims, 9 DrawingFigs.

[51] limit. (31 G031 1/22 [50] Field at Search 226/62- [56] ReferencesCited UNITED STATES ?ATENTS 2,218,763 10/1940 Mery 352/192 2,986,3165/1961 Petersen..... 226/62 X 3,454,334 7/1969 Campbell 352/191 PrimaryExaminerAllen N. Knowles Assistant Examiner-Gene A. ChurchAttorney-Schapp and Hatch ABSTRACT: A motion picture film-advancingmechanism for advancing film having sprocket holes therein instop-and-gc fashion through a film gate for exposure or projection comprising a film-advancing finger means carried on spaced cranks formovement in a circular path for engaging the film and advancing itintermittently in a cyclic action, and a register pin carried for axialmovement in a mounting block and having an eccentric drive for movingthe register pin intermittently into engagement with the film sprocketholes for holding the film when the finger is retracted, said registerpin drive and finger drive mechanism being synchronized through a commongear train and forming for a high-speed operation; the improvementsincluding pivotally carrying the register pin mounting block andproviding an eccentric adjustment screw for adjusting the pivot of theblock and providing fine adjustment of the register pin to obtainaccurate adjustment of the spacing between the register pin and finger,providing a lost motion drive for the register pin whereby the registerpin may 1 be retracted while the finger is in a retracted position, and

providing means for eliminating play and backlash including a pressurebearing member on a ball bearing mounting for e retractable fingers.

PATENTEU AUG] 7 l97| 599,850

sum 2 0r 2 INVIZNTOR,

ERNEST M WH/TLEV A TTOR'IV E V5 MG'LIIGN PICTURE FILM-ADVANQENGMEtIll-IANISM BACKGROUND OF THE IIJVENTEON This invention relates toimprovements in a motion picture film-advancing mechanism, and moreparticularly to improve ments in a film transport apparatus having aclaw or finger mechanism for intermittently advancing film.

Heretofore, high-speed motion picture cameras in which the film isadvanced intermittently, one frame at a time, have been beset by manydifficulties and problems. One of the major problems with suchhigh-speed intermittent motion picture cameras is the physicallimitations of the various parts used, i.e., most of the assembled partsof such high-speed cameras tend to fly apart at speeds in excess of afew hundred frames per second. This physical limitation has dictated themaximum number of frames which can be taken with a camera per second. Inaddition to the speed limitations imposed upon the assembled parts ofthese cameras, the mechanical intricacies of the construction of suchcameras impose operational limitations. The parts must be synchronizedin all respects so that the film is advanced exactly-one frame at a timeand is held against movement to permit a picture to be taken when thefilm is not being advanced. To start, stop and hold the film stationarywhile the film is exposed several hundred times a second involves exactsynchronization which heretofore has been difficult to accomplishwithout making such cameras unduly expensive.

In cameras of the type described, a claw or finger is often employed topull down the film one frame at a time, the claw or finer being drivenrapidly to enter successively into a series of holes in the film foradvancing the latter. The cameras heretofore known to the industry haveemployed complex gear trains for driving and synchronizing the operationof the film advancing claws or fingers. A very slight amount of wear onthese gears creates backlash and runout problems which result in highshock loads, binding and failure of the bearings used for supporting theclaws or fingers. Therefore, it is desirable to provide a film transportmechanism capable of rapid stop-and-go operation in reliablesynchronization, which contains a minimum ofmoving parts.

Another problem that has been encountered in film transport mechanismsresides in the fact that the spacing between holes in a given strip offilm will vary slightly from one strip to another. In fact, the spacingvaries somewhat in the same film due to shrinkage on aging and the like.Such slight variations cause the mechanism to bind somewhat and therebyrun less smoothly or cause damage to the film strip or both.

SUMMARY OF THE INVENTIGN Certain of the problems accompanying filmtransport mechanisms having gear drives are eliminated in the filmtransport apparatus of this invention by employing a crank member andlink system wherein cranks connected to one link are offset or out ofphase from cranks connected to another link of the system, therebypreventing any overcenter binding, preferably this offset is about 90.

One feature of the invention resides in means for moving the registerpin so that its position of engagement may be varied accurately and infine adjustment with respect to the claw or finger utilized tointermittently move the film strip. In its preferred form, thisadjustment is achieved by providing the register pin in a pivotedmounting so that pivoting of the mounting will cause a change inposition of the end of the register pin at its engagement with the filmstrip. The fine adjust ment in this preferred form is best obtained byutilizing an eccentric adjustment screw to accurately adjust the pivotof the register pin mounting block.

In addition to the adjustment means on the register pin, it is preferredto include a manually operable lost motion device in the drive mechanismfor the pin to facilitate loading of the film and adjustment of the pin.However, the lost motion device is locked out during regular operation.

Another feature of the invention, which is incorporated in the preferredform thereof, resides in the use of a special ball bearing construction.This ball bearing construction has the usual inner and outer racewaymembers and balls separating them in combination with a lateral thrustmember formed to slidingly bear against the rotating raceway members andprovide an operative ball bearing contact angle adjusted from thevertical. In this way, better tracking is achieved.

It will be appreciated, that these improved features may be utilizedeither singly or together in combination with Icnown components in orderto provide an improvement thereover and thereby allow higher speeds tobe obtained than heretofore achieved in a reliable manner.

It is therefore a principal object of the present invention to provide acompact, fully synchronized and relatively inexpensive camera in whichthe film is intermittently advanced past an aperture one frame at a timeat the rate of several hundred frames per second or higher.

Another object of this invention is the provision of a highspeed cameraof the class described in which the film is securely held in astationary position between advancing movements so that clear unblurredpictures may be taken.

A further object of the present invention is the provision of ahigh-speed camera such as described in which the distance between thefilm-advancing mechanism and the film-holding mechanism may be adjustedto compensate for minute variations in the distance between sprocketholes in different strips or rolls of film.

A still further object of this invention is the provision of a manuallyoperative lost motion device in the drive means for the film-holdingmechanism to facilitate the loading of the film and the adjusting of thetransport mechanism.

Still another object of the present invention is the provision of ahigh-speed motion picture camera in which the advancing mechanism isconstructed in such a manner as to eliminate vibration and harmonicproblems at very high operating speeds.

Further objects and advantages of the invention will be apparent as thespecification progresses, and the new and useful features of the motionpicture film-advancing mechanism will be more fully defined in theclaims attached hereto.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred form of the invention isillustrated in the accompanying drawings, in which:

FIG. 1 is a side elevation ofa camera constructed according to theinvention with certain of the parts being removed to illustrate thestructure of the film transport mechanism incorporated therein;

FIG. 2, an enlarged vertical fragmentary view of a portion of the camerashown in t'lG. ll illustrating the film transport mechanism as it ismounted therein FIG. 3, a schematic layout of the drive trains utilizedin the preferred film transport mechanism of this invention;

FIG. l, a vertical sectional view taken substantially in the planeofline rl of FM}. 2;

FIG. 3, a sectional view taken substantially in the plane of line d-laof FIG. I;

FIG. 6, a view similar to that shown in FIG. 5, but illustrating analternate position of the mechanism shown therein:

FIG. 7, a horizontal sectional view taken substantially in the planeofline 7-7 ofFIG. 4,

FIG. it, a horizontal view taken substantially in the plane of line MofFIG. 4; and

FIG. 9, a sectional view taken substantially in the plane of line ll-lof FIG.

While only the preferred form of the invention is shown, it should beunderstood that various changes and modifications may be made within thescope of the claims hereto attached without departing from the spirit ofthe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing ingreater detail and more particularly to FIG. 1, there is shown ahigh-speed motion picture camera 11 comprising a housing 12, a lenssystem 13 appropriately mounted thereon, and a film advancing mechanism14 for moving the film in stop and go fashion through an exposureposition. Certain of the usual portions of the camera are not shown, butthe improvement is especially suitable for use in the camera shown inthe US. Pat. No. 3,454,344 issued July 8, 1969 by Rouel R. Campbellentitled Film Transport Apparatus. It will be appreciated, however, thatthis film-advancing mechanism will be suitable in other high-speedcamera constructions, and, also that this film-advancing mechanism maybe utilized to advance film through a movie projector. In such cases,the advantages of the improved high-speed operation of thefilm-advancing mechanism of this invention may be utilized.

Referring again to FIG. 1, the film will move from a supply spool andsuitable associated means (not shown) around roller 16, against aportion of sprocket 17, through a film guide and gate mechanism 18, backagainst the sprocket 17, around roller 19, and finally back to a takeupspool (not shown). The sprocket 17 is driven in synchronous fashion witha drive gear 21, which drives the film-advancing mechanism 14. Drivegear 21 also has gear 22 coupled thereto, and gear 22 serves to drivethe shutter mechanism. In this way, all of the various driven elementsare driven in synchronous relation, and a complete description of atypical synchronized drive system is shown in the Campbell applicationcited above.

The film-advancing means or mechanism 14 is formed to handle a strip offilm 23 having a series of sprocket holes 24 evenly spaced along a sidethereof (see FIG. 3). As there shown, a typical film strip 23 isequipped with sprocket holes on both sides in accordance withconventional construction. The film is advanced through fi m guide 13,which guides the film through a typical aperture in a film gate forexposure thereof.

The film advancing means 14 for intermittently advancing the film 23past the aperture, includes a carrier 26 composed of two plates 27spaced apart from one another by shafts 28 and 29. Each plate 27 has afinger 31 extending from the forward end thereof adapted to be insertedin adjacent holes along one side of the film. A rearwardly extendingfinger 32 is provided on each plate 27 for balancing the latter.Counterweights 33 are connected to shafts 28 and 29 between plates 27(see FIG. 8). The plates are adapted to be driven in a circular motionto cause the fingers 31 to enter into a hole on each side of the Elmstrip in the series of holes on opposite sides of the film and pull thelatter down a predetermined distance before being withdrawn from theholes.

The drive for the carrier 26 includes the drive gear 21, which iscarried on a hollow shaft 34. The hollow shaft is mounted on a shaft 36which is journaled in subassembly block 35. Gear 37 is carried on thehollow shaft 34 as well as the gear 22, so that gears 21, 22 and 37 allrotate at the same time with the shaft 34. Gear 38, which is driven bygear 37, is mounted on shat. 39, which is also journaled intosubassembly block 35. A crank 41 connects gear 38 with a link 42, theopposite end of which is eccentrically connected by crank 43 to a shaft44 rotatably mounted in the block 35.

Shafts 39 and 44 are connected to carrier shafts 28 and 29 by cranks 46and 47, which cranks extend at a 90 angle relative to the arms of cranks41 and 43, i.e., the cranks 46 and 47 are 90 out of phase with respectto the rotation of cranks 41 and 43. As set forth previously, theprovision of the substantially 90 offset between cranks 41, 43 andcranks 46, 47 prevents any binding of the drive mechanism, therebyeliminating binding as a cause of failure. In other words, either link42 or plates 27 will always be out of a dead center position so thatgear 33 will drive the plates continuously and exert sufficient drivingtorque on shaft 44 when rotating shaft 39.

The registration pin means 48 for holding the film against longitudinalmovement when the fingers 31 are not advancing the film is also adaptedto be driven by gear 21. The registration pin means 48 includes aU-shaped pin 49, the outer ends of which are adapted to be inserted intotwo holes on opposite sides of the film (see FIGS. 2, 3 and 7). The pin49 rides on tracks or guides formed in block 51.

The pin 49 is reciprocated toward and away from the film 23 by aregistration pin drive system 52 which includes the shaft 36 driven bygear 21 through the hollow shaft 34 and a pin 53 (see FIG. 5). One endof the shaft 36 is connected to a crank or eccentric 54 adjacent itsother end (see FIGS. 2 and 7 A connecting rod 56 is connecte-l to theeccentric portion of crank 54 and extends toward registration pin 49where it is connected to the pin through a wrist pin 57. It will be seenthat registration pin 49 is reciprocated toward and away from the film23 by means of eccentric crank 54 when the shaft 36 is driven by gear21.

In order to assist in loading the film-advancing mechanism, a manuallyoperable lost motion device is placed in the drive system for theregistration pin. With this device, the film-engaging members may beretracted by bringing the fingers 31 into a retracted position, and thenmanually retracting the registration pin.

Referring more particularly to FIGS. 4 through 6, the lost motion device58 comprises a slot 59 in the hollow shaft 34 having a shoulder 61formed for abutting contact between the pin 53 fixed to shaft 36 andhollow shaft 34. During normal driving operation, the hollow shaft 34 ismoved in the direction indicated by the arrows in FIGS. 5, bringingshoulder 61 against pin 53, and causing shaft 36 to rotate in the samedirection and at the same angular speed as shaft 34. In order tomaintain this normal driving operation in stable condition and preventchattering, a leaf spring 62 is provided as shown in FIG. 5 to urge thepin 53 against shoulder 61.

When it is desired to rotate the shaft 36 and bring the registration pinout of its normal synchronized relation with the finger, the operatorrotates knob 63 while the main drive mechanism is held in stationaryposition so as to cause spring 63 to override its abutment at shoulder64 and ride into an an nular space 66 provided in the hollow shaft forreceiving this spring (see FIG. 6). With the film in place, the operatorwill rotate knob 63 in reverse to bring the registration pins back intothe proper position and place the drive system back into drivingoperation. In doing so, the operator will line up the film strip so thatthe registration pin will fit into the sprocket holes.

In order to insure that the registration pin 49 and fingers 31 willenter into the film at exactly into their proper holes at opposite sidesof the film, the block 51 is made adjustable with respect to thesubassembly block 35. As best seen in FIGS. 4 and 7, the block 51 isgenerally L-shaped and is formed with the main section 67 through whici.the registration pin is carried and a flanged section 68 havingattaching moans thereto for adjustably attaching the block 51 tosubassembly block 35.

The attaching means comprises a pivotal connection through pivotfastening means 69 and eccentric adjustment screw 71 (see FIGS. 2 and7). Auxiliary bolts 72 are provided, each of which have play so as toallow pivoting, but assists in restraining the block 51 from axialmovement away from block 35, and provide for locking the block inadjusted nosition.

Accordingly, the adjusting means allows block 51 to be tilted or cockedslightly (see FIG. 2 for an exaggerated tilt) so that the points ofentry into and exit from the holes in the side of the film may be movedslightly in a vertical direction. In this way, extremely accuratespacing between the registration pin 49 andfingers 31 is provided sothat minor variation in the distance between holes such as is caused byfilm shrinkage can be accommodated so as to assure smooth high-speedoperation without injury to the film.

Another feature of the invention is the provision of special bearings,which assures the desired tightness and thereby assures proper tracking.It is important to provide these special bearings for the relativerotation of the plates 27 around the shafts 2d and 29 in the claw orfinger mechanism. However, it will be appreciated that similar bearingconstructions are also preferably provided for the bearings at link 42,and may be provided for the bearings around shaft 39 and 44, if desired.As here shown, a special bearing construction 73 is utilized on each ofshafts 28 and 33 for providing relative rotational motion between theshafts and the plate 27. FIG. 9 shows the shaft 28 together with itsassociated ball bearing construction 73.

As illustrated in FIG. 9, the bearing 73 is a conventional ball bearinghaving inner race member 7d and outer race member 76 equipped with aplurality of balls 77 fitting in the tracks or raceways of the racemembers. As in the conventional bearing structure, the inner and outerrace members rotate relatively to one another around the rotating balls77.

Since the rotational speeds are extremely high in operation, precisionball bearings should be utilized with minimum clearances and suchbearings are available on the market, having been developed for thegyroscope and other high-speed mechanisms. However, the special bearingmember 73 also contains a springlike washer 78 disposed on one side ofeach bearing assembly; there being a bearing for each plate 27 as shownin FIG. 9. Between the outer race and the springlike washer 78, is athrust bearing 79 made of Teflon or the like and capable of providing alow-friction sliding surface. As here shown, the thrust bearing isconnected to and rotates with the outer race. The washer is in theconfiguration of a relatively flat truncated conic surface, andfabricated from an elastic metal.

It will be appreciated that the force of thrust is quite minimal, andonly sufficient to prevent any slack from existing in the bearingmember. With this thrust being minimal, the actual force of friction isvery low and excessive heat and wear at the sliding surface is therebyavoided.

The advantage of this special bearing structure resides in the fact thatthe ball and race members are provided with an actual contact axisslightly away from the vertical, and the balls track better in thisposition than they do in vertically opposed positions in the racemembers.

In operation, the film is threaded into the camera by opening the filmgate in the conventional manner and inserting the film therein. However,the operator brings the claws or fingers into a retracted position byrotating the takeup reel so as to provide this position of the claw.Then the operator retracts the register pin by rotating knob 63 andforcing the spring out of position as explained above. The film is linedup, and the claw mechanism brought around in a position as shown in H6.2. The register pin then is reset by turning knob 63 back so as to resetthe spring and couple in the lost motion device. This will bring thefilm, register pin and claw substantially in the position shown in FIG.2.

The operator then notices to see if the register pin is going to insertdead center in its corresponding hole with the claw positioned within ahole. if the register pin is in perfect alignment, nothing need be done.However, if the register pin is even slightly off center, the operatorturns eccentric adjusting screw 7ll, which in turn rotates the block Eliand lines up the register pin so as to achieve perfect alignment.Holding screws 72 may be loosened and tightened, if desired, tofacilitate adjustment and lock the pivot in the adjusted position. Withthe film thus accurately aligned with the film-advancing mechanism, themechanism is ready to operate in accordance with the invention.

it will be appreciated, that with the excellent alignment achieved, andthe minimum of drive gears utilized as herein shown together with thebearing construction shown, that the film advancing mechanism is capableof operating at extremely high speeds without injury to the film.

I claim:

1. Apparatus for advancing a strip of film having a series of holestherein, comprising a film-engaging finger formed for selectiveengagement in the holes,

means for moving said finger to effect selective engagement of saidfinger with said holes and move the film strip a desired incrementduring each such engagement,

a register pin formed for selective engagement in the holes,

means for mounting the register pin for axial movement therethrough intoand out of engagement with said film strip,

means for moving said register pin in axial movement to effect selectiveengagement of said register pin with said holes to hold the film stripduring each such engagement,

said means for moving said finger and said means for moving saidregister pin being synchronized so that only one of the two movedelements is engaged in the holes at a given time, and

means for adjusting position of the means for mounting the register pinto adjust the distance between the engagement position of the registerpin and the engagement position of the finger.

2. The apparatus for advancing a strip of film defined in claim 1, inwhich the means for mounting the register pin is a mounting block, andin which the means for moving said register pin includes an eccentricdriven in synchronized relation to the means for moving saidfilm-engaging finger.

3. The apparatus for advancing a strip of film defined in claim 2, inwhich the register pin mounting block is pivotally mounted, and themeans for adjusting the register pin includes an eccentric adjustingscrew for accurately adjusting the degree ofpivot ofthe mounting block.

4. The apparatus for advancing a strip of film defined in claim 1, inwhich a lost motion coupling is provided in the register pin drive meanswhereby the register pin drive may be manually turned in reverse toretract the register pin from engagement in the film while said fingeris also in a disengaged position.

5. The apparatus for advancing a strip of film defined in claim 4, inwhich spring means are provided for ordinarily holding the lost motioncoupling against rearward motion, said spring being biased in a mannersuch that manual operation can override the spring.

6. An apparatus for advancing a strip of film having sprocket holesalong its length, comprising a film-engaging finger means formed forselective engagement of the sprocket holes,

spaced cranks of equal throw connected to said finger means and formedfor moving the latter in a circular path to effect said selectiveengagement of said finger means with the sprocket holes and move thefilm strip a desired increment during each engagement,

drive means for rotating said cranks,

a link connected to said cranks a-d formed for maintaining the throws ofsaid cranks in parallelism as they rotate whereby such finger means isoriented parallel to itself at all positions around said circular path,

a register pin formed for selective engagement in the sprocket holes,

means for mounting the register pin for axial movement therethrough intoand out of engagement with said film strip,

a crank drive means operatively connected to said register pin forproviding said axial movement thereof,

said spaced cranks connected to said finger and said crank drive meansfor operating the register pin being directly driven from a common drivemeans whereby the finger and register pin are synchronized so that onlyone of said moving elements is engaged in a sprocket hole at a giventime, and

means for adjusting the register pin to adjust the distance between theengagement position of the register pin and the engagement position ofthe finger.

7. The apparatus for advancing a strip of film defined in claim 6, inwhich the register pin mounting block is pivotally mounted, and themeans for adjusting the register pin includes an eccentric adjustingscrew for accurately adjusting the degree of pivot of the mountingblock.

8. The apparatus for advancing a strip of film defined in claim 7, inwhich the register pin is formed with two film engagement elementsconstructed to engage sprocket holes on each side of the film, and inwhich the film-engaging finger means has two and only two fingerelements disposed to engage sprocket holes on each side of the film.

$9. The apparatus for advancing a strip of film defined in 7, in which alost motion coupling is provided in the register pin drive means wherebythe register pin drive may be manually turned in reverse to retract theregister pin from engagement in the film while said finger is also in adisengaged position.

10. The apparatus for advancing a strip of film defined in claim 9, inwhich spring means are provided for ordinarily holding the lost motioncoupling against rearward motion, said spring being biased in a mannersuch that manual operation can override the spring.

llll. An apparatus for advancing a strip of film having sprocket holesalong its length, comprising a film-engaging finger means formed forselective engagement of the sprocket holes,

spaced cranks of equal throw connected to said finger means and formedfor moving the latter in a circular path to effect said selectiveengagement of said finger means with the sprocket holes and move thefilm strip a desired increment during each such engagement,

drive means for rotating said cranks,

said finger means being connected to said cranks through ball bearingassemblies,

each of said ball bearing assembly having an inner and outer race withballs disposed therebetween,

a thrust bearing on the rotating race, and a resilient pressure memberadjacent the thrust bearing and formed to urge the rotating race in anaxial direction,

a register pin formed for selective engagement in the sprocket holes,

means for mounting the register pin for axial movement therethrough intoand out of engagement with said film strip,

a crank drive means operatively connected to said register pin forproviding said axial movement thereof,

said spaced cranks connected to said finger and said crank drive meansfor operating the register pin being directly driven from a common drivemeans whereby the finger and register pin are synchronized so that onlyone of said moving elements is engaged in a sprocket hole at a giventime, and

means for adjusting the register pin to adjust the distance between theengagement position of the register pin and the engagement position ofthe finger.

12. The apparatus for advancing a strip of film defined in claim ll, inwhich the resilient pressure member is a washer having the configurationof a relatively flat truncated conic surface and formed of materialhaving high elasticity.

1. Apparatus for advancing a strip of film having a series of holestherein, comprising a film-engaging finger formed for selectiveengagement in the holes, means for moving said finger to effectselective engagement of said finger with said holes and move the filmstrip a desired increment during each such engagement, a register pinformed for selective engagement in the holes, means for mounting theregister pin for axial movement therethrough into and out of engagementwith said film strip, means for moving said register pin in axialmovement to effect selective engagement of said register pin with saidholes to hold the film strip during each such engagement, said means formoving said finger and said means for moving said register pin beingsynchronized so that only one of the two moved elements is engaged inthe holes at a given time, and means for adjusting position of the meansfor mounting the register pin to adjust the distance between theengagement position of the register pin and the engagement position ofthe finger.
 2. The apparatus for advancing a strip of film defined inclaim 1, in which the means for mounting the register pin is a mountingblock, and in which the means for moving said register pin includes aneccentric driven in synchronized relation to the means for moving saidfilm-engaging finger.
 3. The apparatus for advancing a strip of filmdefined in claim 2, in which the register pin mounting block ispivotally mounted, and the means for adjusting the register pin includesan eccentric adjusting screw for accurately adjusting the degree ofpivot of the mounting block.
 4. The apparatus for advancing a strip offilm defined in claim 1, in which a lost motion coupling is provided inthe register pin drive means whereby the register pin drive may bemanually turned in reverse to retract the register pin from engagementin the film while said finger is also in a disengaged position.
 5. Theapparatus for advancing a strip of film defined in claim 4, in whichspring means are provided for ordinarily holding the lost motioncoupling against rearward motion, said spring being biased in a mannersuch that manual operation can override the spring.
 6. An apparatus foradvancing a strip of film having sprocket holes along its length,comprising a film-engaging finger means formed for selective engagementof the sprocket holes, spaced cranks of equal throw connected to saidfinger means and formed for moving the latter in a circular path toeffect said selective engagement of said finger means with the sprocketholes and move the film strip a desired increment during eachengagement, drive means for rotating said cranks, a link connected tosaid cranks and formed for maintaining the throws of said cranks inparallelism as they rotate whereby such finger means is orientedparallel to itself at all positions around said circular path, aregister pin formed for selective engagement in the sprocket holes,means for mounting the register pin for axial movement therethrough intoand out of engagement with said film strip, a crank drive meansoperatively connected to said register pin for providing said axialmovement thereof, said spaced cranks connected to said finger and saidcrank drive means for operating the register pin being directly drivenfrom a common drive means whereby the finger and register pin aresynchronized so that only one of said moving elements is engaged in asprocket hole at a given time, and means for adjusting the register pinto adjust the distance between the engagement position of the registerpin and the engagement position of the finger.
 7. The apparatus foradvancing a strip of film defined in claim 6, in which the register pinmounting block is pivotally mounted, and the means for adjusting theregister pin includes an eccentric adjusting screw for accuratelyadjusting the degree of pivot of the mounting block.
 8. The apparatusfor advancing a strip of film defined in claim 7, in which the registerpin is formed with two film engagement elements constructed to engagesprocket holes on each side of the film, and in which the film-engagingfinger means has two and only two finger elements disposed to engagesprocket holes on each side of the film.
 9. The apparatus for advancinga strip of film defined in 7, in which a lost motion coupling isprovided in the register pin drive means whereby the register pin drivemay be manually turned in reverse to retract the register pin fromengagement in the film while said finger is also in a disengagedposition.
 10. The apparatus for advancing a strip of film defined inclaim 9, in which spring means are provided for ordinarily holding thelost motion coupling against rearward motion, said spring being biasedin a manner such that manual operation can override the spring.
 11. Anapparatus for advancing a strip of film having sprocket holes along itslength, comprising a film-engaging finger means formed for selectiveengagement of the sprocket holes, spaced cranks of equal throw connectedto said finger means and formed for moving the latter in a circular pathto effect said selective engagement of said finger means with thesprocket holes and move the film strip a desired increment during eachsuch engagement, drive means for rotating said cranks, said finger meansbeing connected to said cranks through ball bearing assemblies, each ofsaid ball bearing assembly having an inner and outer race with ballsdisposed therebetween, a thrust bearing on the rotating race, and aresilient pressure member adjacent the thrust bearing and formed to urgethe rotating race in an axial direction, a register pin formed forselective engagement in the sprocket holes, means for mounting theregister pin for axial movement therethrough into and out of engagementwith said film strip, a crank drive means operatively connected to saidregister pin for providing said axial movement thereof, said spacedcranks connected to said finger and said crank drive means for operatingthe register pin being directly driven from a common drive means wherebythe finger and register pin are synchronized so that only one of saidmoving elements is engaged in a sprocket hole at a given time, and meansfor adjusting the register pin to adjust the distance between theengagement position of the register pin and the engagement position ofthe finger.
 12. The apparatus for advancing a strip of film defined inclaim 11, in which the resilient pressure member is a washer having theconfiguration of a relatively flat truncated conic surface and formed ofmaterial having high elasticity.